Self-calibrating antenna system

ABSTRACT

A self-calibrating antenna system having a radio frequency (RF) detector configured to estimate a time delay of a transmission signal on a transmission line, which couples an RF front end with an antenna tuner, based on a magnitude and phase of an input impedance of the transmission line at a first set of a plurality of respective frequencies, and a transceiver configured to transmit to the antenna tuner a calibrated tuning control command based on the estimated time delay to calibrate the antenna tuner and the transmission line.

TECHNICAL FIELD

The present disclosure described herein generally relates to aself-calibrating antenna system, a wireless device havingself-calibrating antenna system, and a method of self-calibrating anantenna system.

BACKGROUND

An antenna tuner is connected between a wireless device's radiofrequency (RF) front end and antenna to improve power transfer bymatching the impedance at the output of the RF front end, which istypically 50 ohms, to the antenna. For any non-50 ohm antenna impedance,the antenna tuner aims to transform the antenna impedance into a 50 ohmimpedance at the input of the antenna tuner such that radiated power ismaximized.

For this purpose, an antenna tuner is operated in a closed loop manner,using the wireless device's RF detector. This RF detector is configuredto detect the impedance loaded at the output of the RF front end. Whenthe characteristics of transmission lines between the RF front end andthe antenna tuner are known, desired impedance at the input of theantenna tuner can be analytically calculated based on the impedancereadout and the frequency of operation.

This closed loop approach requires precise knowledge of the transmissionlines between the RF front end and the antenna tuner. In addition,immediate implementation of carrier aggregation requires multiplicationof antenna modules, and accordingly, the number and complexity oftransmission lines which connect the antenna modules to the RF front endin order to operate the antenna tuner.

From a product rollout perspective, this analytical approach requiressignificant interaction between manufacturers of the RF front end,antenna tuner, and transmission lines. Some manufacturers may not bewilling to provide an accurate characterization of the transmissionlines of the wireless device to be assembled. Transmission linecalibration, which is required in order to operate the antenna tuner ina closed loop manner, is disadvantageous in actual practice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of an example of aself-calibrating antenna system.

FIG. 2 illustrates a schematic diagram of an example of a wirelessdevice comprising the self-calibrating antenna system of FIG. 1.

FIG. 3 is a flowchart illustrating an example of a method ofself-calibrating an antenna system.

DETAILED DESCRIPTION

The present disclosure is directed to a self-calibrating antenna systemhaving a radio frequency (RF) detector configured to estimate a timedelay of a transmission signal on a transmission line, which couples anRF front end with an antenna tuner, based on a magnitude and phase of aninput impedance of the transmission line at a first set of a pluralityof respective frequencies, and a transceiver configured to transmit tothe antenna tuner a calibrated tuning control command based on theestimated time delay to calibrate the antenna tuner and the transmissionline.

The magnitude and phase of the input impedance of the transmission lineenables an estimation of the electrical length of an equivalenttransmission line between the RF front end and the antenna tuner, tothereby determine the antenna tuner's input impedance. The actual lengthof the transmission line does not need to be known. The antenna tunerand the transmission line may then be calibrated based on a shift in thephase of the input impedance, or in other words, based on the estimatedtime delay.

FIG. 1 illustrates a schematic diagram of an example of aself-calibrating antenna system 100. Self-calibrating antenna system 100comprises front end 110, transmission line 120, antenna module 130, andtransceiver 140.

Front end 110 comprises coupler 112, which is configured to probe afixed percentage of energy from forward and reflected waves ontransmission line 120. “Front end” is a generic term for all circuitrybetween transmission line 120 and transceiver 140.

Antenna module 130 comprises antenna tuner 132, transmission line 134,and antenna 136. Antenna tuner 132 is configured to improve powertransfer by matching the impedance at the output of RF front end 110 tothe impedance of antenna 136.

Transceiver 140 comprises firmware 142, RF detector 144, interface 146,and memory 148. RF detector 144 is configured to estimate the inputimpedance of transmission line 120 based on the energy probed by coupler112. This estimated impedance is also referred to as the couplerimpedance, Z_Coupler 122. Interface 146 transmits to antenna tuner 132data signal SDAT, clock signal SCLK, and enable signal VIO. Thistransmission by interface 146 is in response to instructions receivedfrom firmware 142. Memory 148 is configured to store an estimated timedelay of transmission line 120, as described in detail further below.Memory 148 may be a non-volatile memory, and may also be a 16-bitregister, however, the disclosure is not limited in these respects. Thememory may be any known memory suitable for the intended purpose.

Firmware 142 may comprise a non-transitory computer-readable mediumhaving stored thereon a computer program with a program code to beexecuted on a computer.

FIG. 2 illustrates a schematic diagram of wireless device 200 comprisingthe self-calibrating antenna system of FIG. 1. Wireless device 200 maybe, for example, a smart phone, tablet, laptop, etc. Similar referencenumerals shown in FIGS. 1 and 2 represent similar elements.

Device 200 comprises front end 110, transmission line 120, antennamodule 130, and transceiver 140 as described above with respect toFIG. 1. Device 200 also includes a space 250 for a battery. Genericantenna 136 is shown together with antenna feed point 236 for connectingto transmission line 134. Transmission line 120 is shown in more detailthan in FIG. 1 as comprising an exemplary sequence ofcomponents—stripline 121, transition A 123, coaxial cable 125,transition B 127, and stripline 129. Striplines 121 and 129 are RFtransmission lines suitable for printed circuit boards (PCB). TransitionA interconnects two different forms of transmission line—stripline 121located in a PCB and coax 125 suspended in air. Coax 125 is an RFtransmission line suitable for interconnecting two PCBs and configuredto conduct an RF signal between stripline 121 in PCB and stripline 129in another PCB. Transition B interconnects two different forms oftransmission line—coax 125 suspended in air and stripline 129 located ina PCB.

FIG. 3 is a flowchart illustrating an example of a method ofself-calibrating an antenna system 100.

At Step 310, firmware 142 instructs interface 146 to transmit to antennatuner 132 a command to start a self-calibration mode, during which aninput of antenna tuner 132 is set to be 0 ohms.

Next, at Step 320, a magnitude and phase of an input impedance oftransmission line 120, represented as Z_Coupler, are measured by RFdetector 144 at a first set of a plurality of respective frequencies. Inorder to obtain the time delay of interest, impedance measurements at atleast two adjacent frequencies in this single set of a plurality offrequencies is required to derive the electrical length of an equivalenttransmission line between RF coupler 112 of front end 110 and antennatuner 132, and thus the antenna tuner's input impedance may becalculated. However, the disclosure is not limited in this respect;there may be any number of adjacent frequencies measured as suitable forthe intended purpose. The greater number of frequencies measured,generally the greater the accuracy of the time delay estimate. Also, adifference or differences in frequency between the respectivefrequencies of the set may be chosen as required to achieve desiredcalibration accuracy.

The impedances are measured by coupler 112 probing a fixed percentage ofpower from both the forward and reflected waves and routing these twofractional waves to RF detector 144, which performs the actualmeasurement. RF detector 144 then uses these wave measurements toestimate the input impedance of transmission line 120, that is,Z_Coupler 122.

As is known, impedance relates univocally to reflection coefficient,given a fixed reference impedance. In order to measure this reflectioncoefficient, both the forward and the reflected waves, not just thereflected wave, should be measured. This is because the reflectioncoefficient is a complex fraction of a reflected wave relative to thatof the incident wave. Knowing the differences in rotation and frequency,an estimation of the electrical length of an equivalent transmissionline may be determined. The longer the transmission line 120, thegreater the rotation (time delay). Also, the higher the frequency of thetransmission on transmission line 120, the greater the rotation. Thistransmission line estimation is used to perform the calibration, orimpedance transformation, by way of a reflection coefficient shift inphase, or compensation for time delay, which is simple to implement infirmware.

Optionally, Step 320 may be repeated for a second set of a plurality ofrespective frequencies, or as many additional sets of a plurality ofrespective frequencies as desired, as indicated by dotted-line arrow325. Impedance measurements for each additional set of a plurality offrequencies beyond the first set results in more accurate estimations ofthe time delay of transmission line 120. As will be discussed in moredetail below, an average of the time delays for the respective sets offrequencies is used as the estimated time delay for calibrating antennatuner 132 and transmission line 120.

By way of example, assuming N sets of two adjacent frequencies areemployed, and N=3, exemplary sets of a plurality of frequencies could beas follows:

Set A: 710 MHz and 910 MHz (represented in the equations below as f_a1and f_a2, respectively)

Set B: 1710 MHz and 1760 MHz (represented in the equations below as f_b1and f_b2, respectively)

Set C: 1910 MHz and 1960 MHz (represented in the equations below as f_c1and f_c2, respectively)

The magnitude and phase of an input impedance of transmission line 120are measured for each of the foregoing frequencies of sets A, B, and Cand are represented as complex numbers. A complex number comprises realand imaginary components, where the real component represents themagnitude and the imaginary component represents the phase of the inputimpedance. There are 2*N complex impedances arranged in the N (N=3 inthis case) sets of two frequencies.

Next, at Step 330, the time delay (TD) of transmission line 120 isestimated based on the transmission line input impedances that aremeasured by RF detector 144. More specifically, considering N=3, thetime delay is estimated three times. The equations for estimating thesetimes delays are represented as TD_a, TD_b and TD_c in Equations 1-3 asfollows:

TD_a=[(10⁶/720)*(arg{Gamma(f_a1)}−arg{Gamma(f_a2)})/(f_a2−f_a1)  (Equation1)

TD_b=[(10⁶/720)*(arg{Gamma(f_b1)}−arg{Gamma(f_b2)})/(f_b2−f_b1)  (Equation2)

TD_c=[(10⁶/720)*(arg{Gamma(f_c1)}−arg{Gamma(f_c2)})/(f_c2−f_c1)  (Equation3)

“TD” is a time delay magnitude generally expressed in picoseconds, “f”is a frequency value generally expressed in megahertz (MHz), though thedisclosure is not limited to these measurement units. For any of thesets of two frequencies, “f_2” should be greater than “f_1”. “Gamma(f)”is a reflection coefficient at frequency “f” corresponding to thetransmission line input impedance Z_Coupler(f). Z_Coupler and Gammarelate as indicated in Equation 4 as follows:

Gamma=[Z_Coupler−50]/[Z_Coupler+50]  (Equation 4)

Considering that Z_Coupler is a complex number, Gamma is also a complexnumber. A feature of interest in Gamma is its phase in degrees, where itis preferable that 0 degrees<arg(Gamma)<360 degrees. If this is not thecase, unwrapping of arg(Gamma) within a particular frequency set may berequired. Unwrapping means subtracting 360 degrees from the arg(Gamma)for the Gamma at the highest frequency of the two frequencies of theset, that is, f_2. Unwrapping should be performed whenever for aparticular set arg{Gamma(f_2)}>arg{Gamma(f_1)} and is calculated inEquation 5 as follows:

Unwrap{arg{Gamma(f_2)}}=arg{Gamma(f_2)}−360  (Equation 5)

The final time delay which is used to calibrate antenna tuner 132 andtransmission line 120 is an average of the N estimations, in this casethree estimations, and is calculated using Equation 6 as follows:

TD=(TD_a+TD_b+TD_c)/3  (Equation 6)

At Step 340, optionally the estimated time delay TD may be stored inmemory 148

At Step 350, the self-calibration mode is complete, and antenna tuner132 returns to its normal, operational mode.

Optionally, Steps 310-350 may be repeated, such as on a periodic basis,as indicated by the dotted-line arrow 355.

Finally, at Step 360, firmware 142 instructs interface 146 oftransceiver 140 to transmit to antenna tuner 132 a calibrated tuningcontrol command based on the estimated time delay TD. More specifically,when enable signal VIO is high, interface 146 transmits to antenna tuner132 in signal data SDAT a calibrated tuning control command synchronouswith clock signal SCLK. Antenna tuner 132 and transmission line 120 arecalibrated based on this calibrated tuner control command. This methoddescribed herein may be performed after manufacture of a device, such asa wireless device, comprising the antenna tuner and the transmissionline. Alternatively, the method may be performed periodically. Anotheralternative is to perform the calibration after an event resulting indecalibration of the antenna tuner and the transmission line, such asafter exposure to temperatures in a range of, for example, 35° C. or 40°C. or greater. Of course this calibration may be performed during anycombination of these times.

If antenna tuner 132 does not have a calibration mode, this calibrationmethod can still be performed manually by coupling the input of antennatuner 132 with ground by closing switch 138. Step 310 of setting theantenna tuner 132 into self-calibration mode and Step 350 of returningantenna tuner 132 to normal mode would therefore be omitted. This optionis particularly advantageous in test or factory prototypes during amanufacturing process.

The self-calibrating antenna system, wireless device havingself-calibrating antenna control, and method of self-calibrating anantenna system as described herein are advantageous in many respects.

For instance, hardware change of the antenna tuner 132 and/ortransmission lines 120 is not required. This solution is thus costeffective.

Since the electrical length of an equivalent transmission line betweenfront end 110 and antenna tuner 132 is estimated, the actualcharacteristics of the transmission line are not required. This reducesthe number of required interactions between the manufacturers of frontend 110, transmission line 120, and antenna tuner 132.

Antenna system 100 is platform agnostic in that it does not require aspecific antenna tuner 132 or transmission line 120 to beself-calibrated. If antenna tuner 132 itself does not have aself-calibration mode, the calibration can still be performed bycoupling the input of antenna tuner 132 with ground. A wireless devicemanufacturer therefore has the freedom to choose components asconvenient.

Antenna system 100 works for all frequencies of operation that theplatform supports, for example, between 700 and 2,700 MHz, though thedisclosure is not limited in this respect. Also, it can also be extendedto diverse wireless device platforms, such as smart phones, tablets,laptops, etc.

Example 1 is a self-calibrating antenna system, comprising a radiofrequency (RF) detector configured to estimate a time delay of atransmission signal on a transmission line, which couples an RF frontend with an antenna tuner, based on a magnitude and phase of an inputimpedance of the transmission line at a first set of a plurality ofrespective frequencies; and a transceiver configured to transmit to theantenna tuner a calibrated tuning control command based on the estimatedtime delay to calibrate the antenna tuner and the transmission line.

In Example 2, the subject matter of Example 1 can optionally include amemory located in the transceiver and configured to store the estimatedtime delay.

In Example 3, the subject matter of Example 1 can optionally includethat the RF detector is further configured to estimate the time delay ofa transmission signal on the transmission line based on a magnitude andphase of an input impedance of the transmission line at a second set ofa plurality of respective frequencies, and the estimated time delay forcalibrating the antenna tuner and the transmission line is an average ofthe estimated time delay based on the first set of frequencies and theestimated time delay based on the second set of frequencies.

In Example 4, the subject matter of Example 1 can optionally include acoupler, located in the RF front end, and configured to direct a portionof energy of forward and reflected waves of the transmission signal fromthe transmission line to the RF detector.

In Example 5, the subject matter of Example 1 can optionally includethat during calibration, an input impedance of the antenna tuner is setto 0 ohms.

In Example 6, the subject matter of Example 1 can optionally includethat the calibrated tuning control command sets a magnitude of an outputimpedance of the transmission line to 50 ohms.

Example 7 is a wireless device comprising an antenna having an antennaport; and the self-calibrating antenna system of Example 1, coupled tothe antenna port.

In Example 8, the subject matter of Example 7 can optionally includethat the transceiver is configured to transmit the calibrated tuningcontrol command to calibrate the antenna tuner and the transmission lineperiodically.

In Example 9, the subject matter of Example 7 can optionally includethat the transceiver is configured to transmit the calibrated tuningcontrol command to calibrate the antenna tuner and the transmission lineafter an event resulting in decalibration of the antenna tuner and thetransmission line.

Example 10 is a method of self-calibrating an antenna system, the methodcomprising estimating, by a radio frequency (RF) detector, a time delayof a transmission signal on a transmission line, which couples an RFfront end with an antenna tuner, based on a magnitude and phase of aninput impedance of the transmission line at a first set of a pluralityof respective frequencies; transmitting, by a transceiver, to theantenna tuner a calibrated tuning control command based on the estimatedtime delay; calibrating the antenna tuner and the transmission linebased on the calibrated tuning control command.

In Example 11, the subject matter of Example 10 can optionally includecoupling an input of the antenna tuner to ground.

In Example 12, the subject matter of Example 10 can optionally includestoring the estimated time delay in a memory.

In Example 13, the subject matter of Example 10 can optionally includethat the estimating step comprises measuring the magnitude and the phaseof the input impedance of the transmission line at the first set of theplurality of respective frequencies.

In Example 14, the subject matter of Example 13 can optionally includemeasuring a magnitude and phase of an input impedance of thetransmission line at a second set of a plurality of respectivefrequencies; and averaging the estimated time delay based on the firstset of frequencies and the estimated time delay based on the second setof frequencies to result in the estimated time delay for calibrating theantenna tuner and the transmission line.

In Example 15, the subject matter of Example 10 can optionally includethat the estimating, transmitting and calibrating steps are performedduring manufacture of a wireless device comprising the antenna tuner andthe transmission line.

In Example 16, the subject matter of Example 10 can optionally includethat the method is performed after manufacture of a wireless devicecomprising the antenna tuner and the transmission line.

In Example 17, the subject matter of Example 10 can optionally includethat the estimating, transmitting and calibrating steps are performed ina periodic time interval.

In Example 18, the subject matter of Example 10 can optionally includethat the estimating, transmitting and calibrating steps are performedafter an event resulting in decalibration of the antenna tuner and thetransmission line.

In Example 19, the subject matter of Example 10 can optionally includethat the estimating, transmitting and calibrating steps are performed ata time selected from the group consisting of during manufacture of thewireless device, after manufacture of the wireless device, in a periodictime interval, and after an event resulting in decalibration of theantenna tuner and the transmission line.

Example 20 is a non-transitory computer-readable medium having storedthereon a computer program with a program code for performing, when theprogram is executed on a computer, a method of self-calibrating anantenna system, the method comprising estimating a time delay of atransmission signal on a transmission line, which couples an RF frontend with an antenna tuner, based on a magnitude and phase of an inputimpedance of the transmission line at a first set of a plurality ofrespective frequencies; transmitting to the antenna tuner a calibratedtuning control command based on the estimated time delay; andcalibrating the antenna tuner and the transmission line based on thecalibrated tuning control command.

In Example 21, the subject matter of Example 20 can optionally includethat the estimating step comprises measuring the magnitude and the phaseof the input impedance of the transmission line at the first set of theplurality of respective frequencies

Example 22 is a self-calibrating antenna system, comprising a radiofrequency (RF) detecting means for estimating a time delay of atransmission signal on a transmission line, which couples an RF frontend with an antenna tuner, based on a magnitude and phase of an inputimpedance of the transmission line at a first set of a plurality ofrespective frequencies; and a transmitting means for transmitting to theantenna tuner a calibrated tuning control command based on the estimatedtime delay to calibrate the antenna tuner and the transmission line.

In Example 23, the subject matter of Example 22 can optionally includethat the RF detecting means is further for estimating a time delay of atransmission signal on the transmission line based on a magnitude andphase of an input impedance of the transmission line at a second set ofa plurality of respective frequencies, and the estimated time delay forcalibrating the antenna tuner and the transmission line is an average ofthe estimated time delay based on the first set of frequencies and theestimated time delay based on the second set of frequencies.

In Example 24, the subject matter of any of Examples 1-2 can optionallyinclude that the RF detector is further configured to estimate a timedelay of a transmission signal on the transmission line based on amagnitude and phase of an input impedance of the transmission line at asecond set of a plurality of respective frequencies, and the estimatedtime delay for calibrating the antenna tuner and the transmission lineis an average of the estimated time delay based on the first set offrequencies and the estimated time delay based on the second set offrequencies.

In Example 25, the subject matter of any of Examples 1-3 can optionallyinclude a coupler, located in the RF front end, and configured to directa portion of energy of forward and reflected waves of the transmissionsignal from the transmission line to the RF detector.

In Example 26, the subject matter of any of Examples 1-4 can optionallyinclude that during calibration, an input impedance of the antenna tuneris set to 0 ohms.

In Example 27, the subject matter of any of Examples 1-5 can optionallyinclude that the calibrated tuning control command sets a magnitude ofan output impedance of the transmission line to 50 ohms.

Example 28 is a wireless device comprising an antenna having an antennaport; and the self-calibrating antenna system of any of Examples 1-6,coupled to the antenna port.

In Example 29, the subject matter of Example 30 can optionally includethat the antenna tuner and the transmission line are calibrated duringmanufacture of the wireless device.

In Example 30, the subject matter of Example 28 can optionally includethat the antenna tuner and the transmission line are calibrated aftermanufacture of the wireless device.

In Example 31, the subject matter of any of Examples 10-11 canoptionally include storing the estimated time delay in a memory.

In Example 32, the subject matter of any of Examples 10-12 canoptionally include that the estimating step comprises measuring themagnitude and the phase of the input impedance of the transmission lineat the first set of the plurality of respective frequencies.

In Example 33, the subject matter of Example 32 can optionally includethat the estimating step further comprises: measuring a magnitude andphase of an input impedance of the transmission line at a second set ofa plurality of respective frequencies; and averaging the estimated timedelay based on the first set of frequencies and the estimated time delaybased on the second set of frequencies to result in the estimated timedelay for calibrating the antenna tuner and the transmission line.

In Example 34, the subject matter of any of Examples 10-14 canoptionally include that the estimating, transmitting and calibratingsteps are performed during manufacture of a wireless device comprisingthe antenna tuner and the transmission line.

In Example 35, the subject matter of any of Examples 10-14 canoptionally include that the estimating, transmitting and calibratingsteps are performed after manufacture of a wireless device comprisingthe antenna tuner and the transmission line.

In Example 36, the subject matter of any of Examples 10-14 canoptionally include that the estimating, transmitting and calibratingsteps are performed in a periodic interval.

In Example 37, the subject matter of any of Examples 10-14 canoptionally include that the estimating, transmitting and calibratingsteps are performed after an event resulting in decalibration of theantenna tuner and the transmission line.

In Example 38, the subject matter of any of Examples 10-14 canoptionally include that the estimating, transmitting and calibratingsteps are performed at a time selected from the group consisting ofduring manufacture of the wireless device, after manufacture of thewireless device, in a periodic interval, and after an event resulting indecalibration of the antenna tuner and the transmission line.

Example 39 is an apparatus substantially as shown and described.

Example 40 is a method substantially as shown and described.

While the foregoing has been described in conjunction with examples, itis understood that the term “example” is not meant as the best oroptimal. Accordingly, the disclosure is intended to cover alternatives,modifications and equivalents, which may be included within the scope ofthe disclosure.

Although specific examples have been illustrated and described herein,it will be appreciated by those of ordinary skill in the art that avariety of alternate and/or equivalent implementations may besubstituted for the specific examples shown and described withoutdeparting from the scope of the present disclosure. This application isintended to cover any adaptations or variations of the specific examplesdiscussed herein.

1. A self-calibrating antenna system, comprising: a radio frequency (RF)detector configured to estimate a time delay of a transmission signal ona transmission line, which couples an RF front end with an antennatuner, based on a magnitude and phase of an input impedance of thetransmission line at a first set of a plurality of respectivefrequencies; and a processor configured to transmit to the antenna tunerwithin signal data a calibrated tuning control command synchronous witha clock signal and based on the estimated time delay to calibrate theantenna tuner and the transmission line.
 2. The self-calibrating antennasystem of claim 1, further comprising a memory located in the processorand configured to store the estimated time delay.
 3. Theself-calibrating antenna system of claim 1, wherein the RF detector isfurther configured to estimate the time delay of a transmission signalon the transmission line based on a magnitude and phase of an inputimpedance of the transmission line at a second set of a plurality ofrespective frequencies, and wherein the estimated time delay forcalibrating the antenna tuner and the transmission line is an average ofthe estimated time delay based on the first set of frequencies and theestimated time delay based on the second set of frequencies.
 4. Theself-calibrating antenna system of claim 1, further comprising: acoupler, located in the RF front end, and configured to direct a portionof energy of forward and reflected waves of the transmission signal fromthe transmission line to the RF detector.
 5. The self-calibratingantenna system of claim 1, wherein during calibration, an inputimpedance of the antenna tuner is set to 0 ohms.
 6. The self-calibratingantenna system of claim 1, wherein the calibrated tuning control commandsets a magnitude of an output impedance of the transmission line to 50ohms.
 7. A wireless device comprising: an antenna having an antennaport; and the self-calibrating antenna system of claim 1, coupled to theantenna port.
 8. The wireless device of claim 7, wherein the processoris configured to transmit the calibrated tuning control command tocalibrate the antenna tuner and the transmission line periodically. 9.The wireless device of claim 7, wherein the processor is configured totransmit the calibrated tuning control command to calibrate the antennatuner and the transmission line after an event resulting indecalibration of the antenna tuner and the transmission line.
 10. Amethod of self-calibrating an antenna system, the method comprising:estimating, by a radio frequency (RF) detector, a time delay of atransmission signal on a transmission line, which couples an RF frontend with an antenna tuner, based on a magnitude and phase of an inputimpedance of the transmission line at a first set of a plurality ofrespective frequencies; transmitting, by a processor, to the antennatuner within signal data a calibrated tuning control command synchronouswith a clock signal and based on the estimated time delay; andcalibrating the antenna tuner and the transmission line based on thecalibrated tuning control command.
 11. The method of claim 10, furthercomprising: coupling an input of the antenna tuner to ground.
 12. Themethod of claim 10, further comprising: storing the estimated time delayin a memory.
 13. The method of claim 10, wherein the estimating stepcomprises measuring the magnitude and the phase of the input impedanceof the transmission line at the first set of the plurality of respectivefrequencies.
 14. The method of claim 13, wherein the estimating stepfurther comprises: measuring a magnitude and phase of an input impedanceof the transmission line at a second set of a plurality of respectivefrequencies; and averaging the estimated time delay based on the firstset of frequencies and the estimated time delay based on the second setof frequencies to result in the estimated time delay for calibrating theantenna tuner and the transmission line.
 15. The method of claim 10,wherein the estimating, transmitting and calibrating steps are performedduring manufacture of a wireless device comprising the antenna tuner andthe transmission line.
 16. The method of claim 10, wherein the method isperformed after manufacture of a wireless device comprising the antennatuner and the transmission line.
 17. The method of claim 10, wherein theestimating, transmitting and calibrating steps are performed in aperiodic time interval.
 18. The method of claim 10, wherein theestimating, transmitting and calibrating steps are performed after anevent resulting in decalibration of the antenna tuner and thetransmission line.
 19. The method of claim 10, wherein the estimating,transmitting and calibrating steps are performed at a time selected fromthe group consisting of during manufacture of the wireless device, aftermanufacture of the wireless device, in a periodic time interval, andafter an event resulting in decalibration of the antenna tuner and thetransmission line.
 20. A non-transitory computer-readable medium havingstored thereon a computer program with a program code for performing,when the program is executed on a computer, a method of self-calibratingan antenna system, the method comprising: estimating, by a radiofrequency (RF) detector, a time delay of a transmission signal on atransmission line, which couples an RF front end with an antenna tuner,based on a magnitude and phase of an input impedance of the transmissionline at a first set of a plurality of respective frequencies;transmitting, by a processor, to the antenna tuner within signal data acalibrated tuning control command synchronous with a clock signal andbased on the estimated time delay; and calibrating the antenna tuner andthe transmission line based on the calibrated tuning control command.21. The non-transitory computer-readable medium of claim 20, wherein theestimating step comprises measuring the magnitude and the phase of theinput impedance of the transmission line at the first set of theplurality of respective frequencies.